1. Field of the Invention
This invention relates to a sewing machine throat plate construction for deterring a condition referred to as "haloing" in which loose needle thread loops remain above the fabric being stitched.
2. Description of the Prior Art
In the formation of lock stitches by a sewing machine, an eye pointed needle carries a thread through the work fabric where the thread is seized by a loop taker, formed into a needle thread loop, concatenated with a bobbin thread, and then drawn up or set into the fabric to form a stitch. The loop of needle thread seized by the loop taker is comprised of two limbs; the work limb extending from the loop taker to the previous stitch; and the take-up limb extending from the loop taker to the thread supply. If the work limb is frictionally interengaged by the take-up limb in its upward excursion, the work limb may be drawn above the surface of the fabric and form a loose stitch or halo.
Prior known anti-haloing devices carried on the throat plate have provided slots or passageways for frictionally restraining the work limb to prevent interengagement of the two thread limbs.
One problem with prior known anti-haloing throat plates is that they constrain the needle thread loop in disadvantageous positions which must be compensated for by other components of the sewing machine thread handling system.
Another problem is that they may not be optimally suited for use with a wide range of thread types and thicknesses.
Still another problem is that they unnecessarily complicate the construction of a throat plate.